In-wheel motor with motor position sensor and brake system

ABSTRACT

A vehicle wheel assembly comprises: a wheel for mounting a tire thereon; and an in-wheel motor mounted in the inner space of the wheel and comprising: a rotor connected to the wheel, wherein a magnet is mounted to a center portion of the rotor rotatably coupled with a bearing assembly and arranged at a rotation axis of the wheel, a stator configured to drive the rotor, a rotary sensor disposed in sensing relationship with the magnet mounted to the center portion of the rotor, the rotary sensor configured to be responsive to rotation of the magnet for generating a signal, and an electronic device comprising a circuit board and electronics; and a brake actuator configured to apply brake to the wheel or the rotor. The electronics mounted on the circuit board comprise a single electronic control unit configured to control both the in-wheel motor and the brake actuator.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Patent Application Ser. No.62/985,318, filed on Mar. 4, 2020, entitled “INTEGRATED IN-WHEELPROPULSION ASSEMBLY”, which is all hereby incorporated herein byreference in its entirety.

BACKGROUND

Various embodiments of the present disclosure generally relate to anelectric motor for rotating a wheel on a vehicle and electronicsassociated with operation and drive of the electric motor, and moreparticularly to an in-wheel electric motor with a motor position sensorand a brake system.

Most commercially available vehicles use an internal engine to drive twoor more of vehicle wheels. However, electric wheel motors, in which amotor structure is integrally mounted with a wheel to rotate the wheeland drive a vehicle, have been proposed in vehicle applications,particularly in electric and hybrid automobiles. The electric wheelmotor could drive a vehicle with minimal or no use of the vehicle's mainengine because the electric motor is incorporated in a vehicle wheel.The design may eliminate traditional drivetrain components such astransmission, axles, differential universal joints, driveshafts, and acentral engine or motor. Electric vehicles can use the in-wheel electricmotor to provide both drive or propulsion for the vehicle andregenerative braking for stopping the vehicle. Road wheels are drivenand braked by the in-wheel electric motors supported coaxially withinthe wheels. The in-wheel electric motors are arranged to provide aregenerative braking effect that simultaneously retards wheel rotationand charges a vehicle battery. The use of in-wheel motors on a vehicleallows for precise control of power in and out of each wheelindividually, which may result in improved drivability, handling andbraking. Currently emerging key technologies are in-wheel motors,electric braking, integrated steering activators, and active suspensioncombined with embedded sensors and real time computation. These electricvehicle drive units have the potential to go beyond current applicationsand lead to novel vehicle architectures and a new vehicle culture.

It is with respect to these and other general considerations that thefollowing embodiments have been described. Also, although relativelyspecific problems have been discussed, it should be understood that theembodiments should not be limited to solving the specific problemsidentified in the background.

SUMMARY

The features and advantages of the present disclosure will be morereadily understood and apparent from the following detailed description,which should be read in conjunction with the accompanying drawings, andfrom the claims which are appended to the end of the detaileddescription.

According to various exemplary embodiment of the present disclosure, avehicle wheel assembly may comprise: a wheel for mounting a tire thereonand having an inner space; an in-wheel motor mounted in the inner spaceof the wheel and configured to drivingly rotate the wheel, the in-wheelmotor comprising: a rotor connected to the wheel, wherein a magnet ismounted to a center portion of the rotor rotatably coupled with abearing assembly and arranged at a rotation axis of the wheel, a statorconfigured to drive the rotor, wherein the rotor is configured to berotatable relative to the stator, a rotary sensor disposed in sensingrelationship with the magnet mounted to the center portion of the rotor,the rotary sensor configured to be responsive to rotation of the magnetfor generating a signal, and an electronic device comprising a circuitboard and electronics mounted on the circuit board; and a brake actuatorconfigured to apply brake to the wheel or the rotor. The electronicdevice configured to control the in-wheel motor and the brake actuatormay be positioned in an inner cavity formed in the stator.

The electronics mounted on the circuit board comprise a singleelectronic control unit configured to control both the in-wheel motorand the brake actuator. The electronics of the electronic devicepositioned in the inner cavity formed in the stator may comprise: afirst switch module configured to control current supplied to conductorsof the stator, a second switch module configured to control powersupplied to the brake actuator, and a single electronic control unitconfigured to control the first switch module for the stator and thesecond switch module the brake actuator.

The vehicle wheel assembly may further comprise: two-phase dielectricmaterial; and one or more covers coupled with the stator to form ahermetic enclosure, wherein the electronic device and the two-phasedielectric material are contained in the hermetic enclosure formed by awall of the stator and the one or more covers coupled with stator, andthe two-phase dielectric material is in contact with the wall of thestator and the electronic device so that the two-phase dielectricmaterial changes temperature of the stator and the electronic device bytransitioning between a liquid phase and a gaseous phase, conduction,and convection. A wire may electrically connect the circuit boardcontained within the hermetic enclosure and the rotary sensor disposedoutside the hermetic enclosure so that an electronic control unitmounted on the circuit board receives the signal generated by the rotarysensor.

The rotary sensor and the magnet of the rotor mounted to the centerportion of the rotor may be arranged to be collinear with the rotationaxis of the wheel. The magnet of the rotor mounted to the centralportion of the rotor and the rotary sensor are disposed between thebearing assembly and a vehicle frame or body. The magnet may be mountedto a distal end of the central portion of the rotor.

At least a part of the center portion of the rotor, which is coupledwith the bearing assembly and the magnet is mounted to, may bepositioned inside the inner cavity of the stator, and other magnetsincluded in the rotor may radially surround an outer surface of thestator.

In certain exemplary embodiments of the present disclosure, the in-wheelmotor may be configured to have 48 stator slots and 40 rotor poles.

By locating a magnet at the center portion of the rotor of the in-wheelmotor for sensing a motor position of the in-wheel motor and physicallyintegrating a processor or electric control unit for the electric motorand another processor or electric control unit for the brake actuator toa single processor or electronic control unit, certain embodiments ofthe present disclosure may reduce manufacturing cost and result inconvenient packing of the vehicle wheel assembly, and may make easier tosynchronize brake control and load and remove necessity ofintercommunication between separate processors or electronic controlunits for the electric motor and the brake actuator.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments in accordance with the present disclosure will bedescribed with reference to the drawings, in which:

FIG. 1 is a front perspective view of a vehicle wheel assembly accordingto an exemplary embodiment of the present disclosure;

FIG. 2 is a rear view of a vehicle wheel assembly according to anexemplary embodiment of the present disclosure;

FIG. 3 is an exploded view of a vehicle wheel assembly according to anexemplary embodiment of the present disclosure;

FIG. 4 is a partial cross-sectional view of a vehicle wheel assemblytaken at cross-section A-A of FIG. 2 according to an exemplaryembodiment of the present disclosure;

FIG. 5 is a cross-sectional and inside view of a vehicle wheel assemblyaccording to an exemplary embodiment of the present disclosure;

FIG. 6 is a perspective view of an electric device included in a vehiclewheel assembly according to an exemplary embodiment of the presentdisclosure;

FIG. 7 is a rear perspective view of a vehicle wheel assembly accordingto an exemplary embodiment of the present disclosure; and

FIG. 8 shows a schematic view of a vehicle according to an exemplaryembodiment of the present disclosure.

Corresponding numerals and symbols in the different figures generallyrefer to corresponding parts unless otherwise indicated. The figures aredrawn to clearly illustrate the relevant aspects of the embodiments andare not necessarily drawn to scale.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings which form a part of the present disclosure, andin which are shown by way of illustration specific embodiments in whichthe invention may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice theinvention, and it is to be understood that other embodiments may beutilized and that structural, logical and electrical changes may be madewithout departing from the spirit and scope of the invention. Thefollowing detailed description is therefore not to be taken in alimiting sense, and the scope of the invention is defined only by theappended claims and equivalents thereof. Like numbers in the figuresrefer to like components, which should be apparent from the context ofuse.

Referring to FIGS. 1, 3, 4 and 8, a vehicle wheel assembly 10 includesan electric in-wheel motor 100 and a wheel 110. The vehicle wheelassembly 10 may be coupled to a vehicle body or frame 25 and/or othersuitable suspension components of a vehicle 20 via a connectionstructure 600 (e.g. an axle, knuckle or upright). The in-wheel motor 100may be disposed within the wheel 110. A tire 115 is mounted on andsecured to an outer circumferential surface of the wheel 110. Thevehicle wheel assembly 10 may be installed at each of all four wheels110-1 to 110-4 of the vehicle 10. Alternatively, the vehicle wheelassembly 10 may be incorporated into only two front wheels 110-1, 110-2or only two rear wheels 110-3, 110-4 of the vehicle 20. The vehicle 20may have a battery 30 for supplying a power source for the in-wheelmotor 100. The battery 30 is electrically connected to the in-wheelmotor 100 via a connector and wire 756 of FIGS. 2, 4 and 7.

Referring to FIGS. 3-5, the in-wheel motor 100 generally includes astator 200, and a rotor 300. The stator 200 and the rotor 300 aredisposed inside a wheel cavity 112 of FIG. 3. The rotor 300 may bespaced apart from the stator 200 by a radial air gap. The rotor 300 maybe disposed concentric with the stator 200. The stator 200 and the rotor300 each may be disposed about a rotation axis R of the wheel 110.Although some embodiments of the present disclosure show that the stator200 may be disposed within the rotor 300, the stator 200 may be disposedoutside the rotor 300.

Stator & Rotor

The stator 200 includes a stator core 220. The stator core 220 may begenerally cylindrical in shape. The stator core 220 (e.g. iron core) maybe made of a stack of stator laminations and extend along the rotationaxis R. An outer surface of the stator core 220 may be formed by aplurality of stator teeth. The stator teeth of the stator core 220 maybe arranged circumferentially and may protrude toward the rotor 300. Thestator core 220 may include a substantially circular inner wall 260. Theinner wall 260 of the stator core 220 may form an inner cavity withinthe stator 120 that is configured to receive an electronic device 400.

A winding arrangement for conductors 250 that form one or moreelectromagnets by carrying an excitation current is comprised in thestator 200. The windings of the conductors 250 are formed on statorpoles. Current flowing through the conductors 250 generates a statorelectromagnetic flux. The stator electromagnetic flux may be controlledby adjusting the magnitude and frequency of the current flowing throughthe conductors 250. The conductors 250 may be encapsulated with pottingmaterial (e.g. epoxy potting material). Wires or leads from the windingsof the conductors 250 extend for connection to the electronic device400. For example, the conductors 250 of the stator 200 is electricallyconnected to a first switch module 430 of the electronic device 400 ofFIG. 6 via the wires or leads such that the first switch module 430 ofthe electronic device 400 can control current flowing on the windings ofthe conductors 250.

The connection structure 600 (e.g. an axle, knuckle or upright) couplesthe stator 200 to a frame or body 25 of the vehicle 20. The connectionstructure 600 is arranged to prevent any substantive rotation of thestator 200 relative to other non-rotating elements of the vehicle 20while allowing the stator 200 to move in other degrees of freedom.

The rotor 300 may include the plurality of permanent magnets 310preferably arranged around the inside of a rotor core or rotor back iron320 (e.g. silicon steel, nickel iron, amorphous iron, and the like),which is attached to a rotor housing 330. Alternatively, the permanentmagnets 310 may be directly mounted on the rotor housing 330 without therotor core or rotor back iron 320. The magnets 310 may alternate inmagnetic polarity along the radial air gap across from the stator 200.

The stator flux generated by the wiring arrangement of the conductors250 of the stator 200 and the rotor flux generated by the permanentmagnet 310 of the rotor 300 may be distributed in the air-gap betweenthe stator 200 and the rotor 300. Interaction between the stator fluxand the rotor flux causes the rotor 300 to rotate relative to the stator200.

The rotor 300 is attached to the stator 200 or the connection structure600 (e.g. an axle, knuckle or upright) via a bearing assembly 500. Forexample, as shown in FIG. 4, a center portion 340 of the rotor 300 (e.g.an outer radial wall of the center portion 340 of the rotor 300) may berotatably coupled with the bearing assembly 500 and arranged at therotation axis R of the wheel 110 so that the rotor 300 can rotate aroundthe rotation axis R of the wheel 110. The bearing assembly 500 mayinclude one or more bearings, for instance, but not limited to, a ballbearing or a roller bearing.

For example, the bearing assembly 500 comprises two parts, anon-rotatable part 510 fixed to the stator 200 or the connectionstructure 600 and a rotatable part 520 fixed to the rotor 300. The rotor300 is rotationally coupled to the vehicle 20 via the bearing assembly500 at the center portion 340 of the rotor 300. The rotor housing 330can be fixed to the center portion 340 of the rotor 300 using bolts 342to fix the rotor housing 340 to the center portion 340 of the rotor 300and consequently firmly onto the rotatable part 520 of the bearingassembly 500. Alternatively, the center portion 340 of the rotor 300 isformed integrally with the rotor housing 330 as a single piece body. Thecenter portion 340 of the rotor 300 may protrude from the front portionof the rotor 300 facing the outside of the vehicle 20 toward the vehicleframe or body 25. Although two sets of ball bearings are illustrated inFIG. 5, a single or three or more ball bearing sets of ball bearings orother type of bearings can be used if appropriate.

Motor Position Sensor Assembly & Magnet Assembly

Referring to FIG. 4, a magnet assembly 350 is fixed to the centerportion 340 of the rotor 300. For example, the magnet assembly 350 isarranged on the distal end of the center portion 340 of the rotor 300.The magnet assembly 350 may comprise a magnet holder 352. The magnetholder 352 may have an inner space for holding a magnet 354. The magnet354 is positioned within the inner space of the magnet holder 352 suchthat the magnet 354 produces magnetic flux which flows from the magnet354 to a rotary sensor 361. For example, the magnet holder 352 may atleast substantially surround the magnet 354. The magnet holder 352 ismade of, for example, but not limited to, non-magnetic material such asbrass, aluminum, potting material, plastic, a synthetic resin material,stainless steel, copper, and the like. The magnet holder 352 includes afixing structure or means 356 configured to fixing the magnet 354 to thecenter portion 340 of the rotor 300. For instance, the fixing structureor means 356 of the magnet holder 352 has an opening which is insertedinto the distal end of the center portion 340 of the rotor 300 and awall that contacts the center portion 340 of the rotor 300 and holds themagnet holder 352 and the center portion 340 of the rotor 300 together.In the magnet holder 352, the non-magnetic material 358 may be disposedbetween the center portion 340 of the rotor 300 and the magnet 354. Inanother example, the non-magnetic material 358 may be part of the magnetholder 352. Alternatively, the magnet holder 352 may have an air gapbetween the center portion 340 of the rotor 300 and the magnet 354.

Instead of the structure of the magnet holder 352 illustrated in FIG. 4,the magnet holder can be implemented as an adhesive made of non-magneticmaterial. Any material that can hold the magnet 354 and the centerportion 340 of the rotor 300 together and reduce leakage magnetic fluxfrom the magnet 354 to the center portion 340 of the rotor 300 can beused for the adhesive.

A motor sensor position assembly 360 may comprise the rotary sensor 361.The rotary sensor 361 may be disposed in sensing relationship with themagnet 354 attached to the center portion 340 of the rotor 300. Therotary sensor 361 may be in close proximity to the magnet 354. Forexample, the rotary sensor 361 may be positioned adjacent to, or alignedwith, the distal end of the center portion 340 of the rotor 300 (or themagnet 354). The rotary sensor 361 is responsive to the rotation of thecenter portion 340 of the rotor 300 (or the magnet 354). Upon therotation of the center portion 340 of the rotor 300, the magnetic fieldgenerated by the magnet 354 mounted to the center portion 340 of therotor 300 will appear to the rotary sensor 360 as a rotating magneticfield that may be used to monitor a rotational position, movement, orstatus of the rotor 300. The rotary sensor 361 measures the magneticfield generated by the magnet 354. The measurements obtained by therotary sensor 361 are used to calculate, for example, but not limitedto, one or more of radial position, rotations per minute (RPM),direction of rotation of the rotor 300 and the like. The rotary sensor361 may generate an output signal indicative of the detected ormonitored result associated with the magnet 354 (or the center portion340 of the rotor 300) such as magnetic field/flux measurement results. Aprocessor 410 (or an integrated electronic control unit (ECU)) mountedon a circuit board 420 of the electronic device 400 can calculate theradial position, rotations per minute (RPM), direction of rotation ofthe rotor 300 based on the output signal of the rotary sensor 361. Therotary sensor 361 can be any suitable device(s) for generating signalresponsive to the rotation of the center portion 340 of the rotor 300(or the magnet 354). For example, the rotary sensor 361 can be an analogor digital type sensor responsive to a magnetic field. The rotary sensor361 may be a Hall effect sensor, a magnetoresistive (MR) sensor, or anyother sensor known in the art with similar capabilities.

A magnetic shield 362 may surround the magnet 354 and the rotary sensor361. For example, the magnet 354 and the rotary sensor 361 may bepositioned at the center, or at least along the same longitudinal axis,of the magnetic shield 362. The magnetic shield 362 may act to encompassthe magnetic flux from the magnet 354 to the rotary sensor 361 and alsoto shield the rotary sensor 361 from any external magnetic field such asstray field or magnetic field from the outside of the magnetic shieldand magnetic field generated by the electric motor 100. The magneticshield 362 may protect the rotary sensor 361 from influences outside themagnetic shield 362. Further, by having the magnetic shield 362 at leastsubstantially surround the magnet 354, the magnetic flux generated fromthe magnet 354 does not extend out of the magnetic shield 362. Themagnetic shield 362 may be cylindrically-shaped. However, across-section of the magnetic shield 362 can have any shape such as anoval, square, rectangle, triangle, diamond, and so forth. The magneticshield 362 is made of, for example, but not limited to, soft magneticmaterial. The soft magnetic material generally has a small remanencefield. Conversely, the soft magnetic material loses most of itsmagnetization when an applied field is removed. The soft magneticmaterial may have high saturation flux density (i.e. greater than 0.5Tesla) and high relative permeability (i.e. greater than 100). Examplesof the soft magnetic material include, but are not limited to, pure orsoft iron, steel alloy, low carbon steel with carbon less than 4%,Iron-Cobalt (Fe—Co) alloys, Iron-Nickel-Cobalt (Fe—Ni—Co) alloys, orIron-Nickel (Fe—Ni) alloys such as permalloy. For instance, the magneticshield 362 may be a hollow steel ring.

The rotary sensor 361 is electrically connected to the electronic device400, such as the circuit board 420, through a cable, wire or any othersuitable means 451 in order to transmit to the integrated processor orECU 410 the output signal indicative of the detected or monitored resultassociated with the magnet 354 (or the center portion 340 of the rotor300) such as magnetic field/flux measurement results, the radialposition, RPM, or direction of rotation of the rotor 300. The outputsignal of the rotary sensor 361 may be used by the integrated processoror ECU 410 to control the electric motor 100 and a brake actuator 800.

Brake Actuator

The vehicle wheel assembly 10 may further comprise the brake actuator800. The brake actuator 800 may be configured to apply brake to thewheel 110 or the rotor 300 using a variety of ways. The brake actuator800 may be an electro-mechanical braking system (EMB) actuator. Forexample, the brake actuator 800 actuates or drives an electric motorincluded in the brake actuator 800 to engage a brake pad with a brakedisc 370. The brake pad may be coupled to the motor of the brakeactuator 800 through various coupling means, for example, piston, gearand/or nut-spindle assemblies, but not limited thereto. The brake disc370 may be fixed or operatively connected to the wheel 110 or the rotor330 for rotation with the wheel 110 or the rotor 330. The brake actuator800 may supply braking force to the brake disc 370 of the wheel 110 orthe rotor 330. The brake actuator 800 may be fixedly installed to anysuitable portion of the vehicle wheel assembly 10, for example, but notlimited to, the stator 200 or the connection structure 600 (e.g. anaxle, knuckle or upright). Exemplary embodiments of the brake actuator800 are disclosed in U.S. patent application Ser. No. 16/118,437,entitled “ELECTROMECHANICAL ACTUATOR PACKAGE WITH MULTI-STAGE BELT DRIVEMECHANISM”, filed on Aug. 31, 2018, which is all hereby incorporatedherein by reference in its entirety.

Although electronics for controlling the brake actuator 800, such as aprocessor or ECU, switches, inverter, and power supplier, can bearranged inside the package of the brake actuator 800, some exemplaryembodiments of the present disclosure can remove the processor or ECU,switches, inverter, and power supplier for controlling the brakeactuator 800 from the brake actuator package. Instead, according tocertain exemplary embodiments of the present disclosure, the processoror ECU for controlling the brake actuator 800 can be integrated with aprocessor or ECU for controlling the electric motor 100 as a singleintegrated processor or ECU. Alternatively, the processor or ECU forcontrolling the brake actuator 800 separate from the processor or ECUfor controlling the electric motor 100 can be mounted to the circuitboard 420 disposed in the stator 200, and therefore both the processoror ECU for controlling the brake actuator 800 and the processor or ECUfor controlling the electric motor 100 are arranged on the circuit board420. Further, switches or inverters for controlling power supplied tothe brake actuator 800 also can be arranged on the circuit board 420disposed in the stator 200 instead of the inside of the package of thebrake actuator 800.

Electronic Device

Referring to FIG. 6, the electronic device 400 may comprise the circuitboard 420. Any suitable circuitry and electronic components, such as amicroprocessor, may be mounted on the circuit board 420. The electroniccomponents carried by the circuit board 420 include a number of switcheswhich may typically comprise one or more semiconductor devices such asmetal-oxide-semiconductor field-effect transistors (MOSFETs) orinsulated-gate bipolar transistor (IGBTs), or any suitable knownswitching circuit or current regulator. For example, a first switchmodule 430 may be configured to control the in-wheel motor 100. Thefirst switch module 430 drives the windings of the conductors 250 of thestator 200. The first switch module 430 may control current supplied tothe windings of the conductors 250 of the stator 200 such that theelectromagnets in the stator 200 can provide a magnetic field forproviding a rotation motion to the permanent magnets 310 of the rotor300 in response to the current supplied by the first switch member 430.A second switch module 440 may be configured to control power suppliedto the brake actuator 800.

The first and second switch modules 430 and 440 may be an inverter whichis a circuitry that changes direct current (DC) to alternating current(AC). The DC power is supplied to the first and second switch modules430 and 440, and the first and second switch modules 430 and 440 maygenerate a multi-phase (e.g. three-phase) voltage supply for driving thein-wheel motor 100 and the brake actuator 800 in response to controlsignals of the integrated processor or ECU 410. Each of the first andsecond switch modules 430 and 440 may include one or more switches suchas MOSFETs, IGBTs, or any type of semiconductors, and the number ofswitches included in the first and second switch modules 430 and 440 maydepend upon the number of voltage phases to be applied to the in-wheelmotor 100 or the brake actuator 800.

The electronic device 400 may further include a capacitor module 450.The capacitor module 450 may filter current flow and reduce voltageripple, and distribute the DC power supply to the first and/or secondswitch modules 430 and 440. To reduce the effects of inductance on thefirst and second switch modules 430 and 440 when switching current, thecapacitor module 450 may be used as a local voltage source for the firstand second switch modules 430 and 440. By placing the capacitor module450 close to the first and second switch modules 430 and 440, theinductance associated with the voltage source is minimized. For example,the capacitor module 450 is mounted on a surface of the circuit board420 opposite to the other surface of the circuit board 420 on which thefirst and second switch modules 430 and 440 are mounted. The capacitormodule 450 may be an annular type capacitor, but the capacitor module450 may be of any shape.

The integrated processor or ECU 410 may be configured to control boththe electric motor 100 and the brake actuator 800. For example, theintegrated processor or ECU 410 may control the first switch module 430and the second switch module 440 in order to control current or powersupplied to the stator 200 of the motor 100 and the brake actuator 800.The integrated processor or ECU 410 may receive the output signalindicative of the detected or monitored result associated with themagnet 354 mounted on the center portion 340 of the rotor 300 from therotary sensor 361, and the integrated processor or ECU 410 may controlthe first switch module 430 and the second switch module 440 based onthe output signal of the rotary sensor 361.

The processor or ECU 410 may be a single physically-integrated processoror ECU that is configured to control both the electric motor 100 and thebrake actuator 800 instead of having two separate processors or ECUs,one for controlling the electric motor 100 and the other for controllingthe brake actuator 800. Physical integration of the processors or ECUsfor the electric motor 100 and the brake actuator 800 to a singleprocessor or ECU 410 may make easier to synchronize brake control andload, and remove necessity of intercommunication between separateprocessors or ECUs for the electric motor 100 and the brake actuator800. And, it may reduce manufacturing cost and result in convenientpacking of the vehicle wheel assembly 10.

The integrated processor or ECU 410 is configured to perform a driveoperation for providing a drive torque by controlling the in-wheel motor100 as well as a brake operation for providing a brake torque bycontrolling either or both of the in-wheel motor 100 and the brakeactuator 800. For example, during the brake operation, the integratedprocessor or ECU 410 controls the in-wheel motor 100 to provide a brakeforce and/or controls the brake actuator 800 to apply the brake to thewheel 110 or the rotor 300. Generally, most (around 85%) of the brakingcan be performed by the control of the electric in-wheel motor 100. Incase of failure of performing the braking operation of the electricmotor 100, the brake actuator 800 may apply the brake to the wheel 110or the rotor 300.

Alternatively, instead of a single physically-integrated processor orECU, two separate processors or ECUs, one for controlling the electricmotor 100 and the other for controlling the brake actuator 800, may bemounted to the circuit board 420.

The circuit board 420 further includes a connector 461 configured toreceive one or more electrical wires or cables 710 electricallyconnecting between the brake actuator 500 and the circuit board 420, andthe circuit board 420 electrically connects one or more of the processoror ECU 410, the first switch module 430 and the second switch module 440to the connector 461 so that one or more of the processor or ECU 410,the first switch module 430 and the second switch module 440 mounted tothe circuit board 420 can be electrically connected to the brakeactuator 800. The connector 461 has one or more electrical wires. Oneend of the electrical wire of the connector 461 may be electricallyconnected to the circuit board 420, and the other end of the electricalwire of the connector 461 may be a pin which can be connected with anelectrical terminal of the electrical wires or cables 710.

Hermetic Enclosure & Two-Phase Dielectric Material

The electronic device 400 may be fixed to the stator 200. For instance,the circuit board 420 is retained in an inner hollow space 280 formedwithin the stator 200 by any suitable manner, such as by a plurality ofclips or snaps integrally formed in the stator 200 and/or the cover700-1, 700-2 or screws. Covers 700-1, 700-2 are assembled together withthe stator 200 so that the inner wall 260 of the stator 200 and thecovers 700-1, 700-2 can form a hermetic enclosure 270. The covers 700-1,700-2 and the stator 200 may be assembled together by any suitablemeans, for example, but not limited to, bolts 701 and/or adhesive.

The hermetic enclosure 270 formed by the inner wall 260 of the stator200 and the covers 700-1, 700-2 is a hermetically sealed, leakage-freeenclosure in order to prevent the leakage of two-phase dielectricmaterial 290 contained in the hermetic enclosure 270. A center portionof at least one of the covers 700-1, 700-2 may protrude toward the otherof die covers 700-1, 700-2 to be coupled to each other. An outer edgeportion of each cover 700-1, 700-2 is fixed to the stator 200, and aninner edge portion of each cover 700-1, 700-2 is coupled with eachother. The circuit board 420 is fixed inside the hermetic enclosure 270formed by the inner wall 260 of the stator 200 and the covers 700-1,700-2. Although some embodiments of the present disclosure have twocovers 700-1, 700-2, three or more covers can be coupled to the stator200 to form the hermetic enclosure 270. And, the inner wall 260 of thestator 200 and the covers 700-1, 700-2 are not necessary to beimplemented as separate individual pieces, and the inner wall 260 of thestator 200 and the covers 700-1, 700-2 may be implemented as a singlepiece housing forming the hermetic enclosure.

The two-phase dielectric material 290 is contained within the hermeticenclosure 270 formed by the inner wall 260 of the stator 200 and thecovers 700-1, 700-2 in order to cool the electronic device 400 includingthe processor or ECU 410, the circuit board 420, the first switch module430, the second switch module 440, the capacitor module 450, and anyother electronic components mounted on the circuit board 420. Thehermetic enclosure 270 may form a cooling channel allowing the two-phasedielectric material 290 to flow around the electronic device 400 andalong the inner wall 260 of the stator 200 within the hermetic enclosure270. Unwanted non condensable gases (e.g. air) shall also be preventedfrom entering by the seals. A part or whole of the electronic device 400is submerged in the two-phase non-conductive liquid in the hermeticallysealed, leakage-free enclosure 270. For example, 30% to 90% of a volumeof the hermetic enclosure 270 may be filled with the two-phasedielectric material 290 to efficiently adjust the temperature of thestator 200 and the electronic device 400 by the phase transition betweena liquid state and a gas state, conduction, and convection.

The two-phase dielectric material 290 can fluidly travel within thehermetic enclosure 270 and is in contact with the inner wall 260 of thestator 200 and the electronic device 400 so that the two-phasedielectric material 290 can get rid of excess heat generated by thestator 200 and the electronic device 400 by transitioning between aliquid phase and a gaseous phase. The two-phase dielectric material 290may use a low-temperature evaporation process to cool hot electronicsand transfer the heat out of the liquid. The heat generated by thestator 200 and the electronic device 400 boils the two-phase dielectricmaterial 290 and changes the phase of the two-phase dielectric material290 from liquid to gas, and this change pulls the heat away from thestator 200 and the electronic device 400. The two-phase dielectricmaterial 290 in the gas phase contacts the covers 700-1, 700-2 coupledto the stator 200, and is cooled again by a heat exchanging method toallow return into the liquid phase. For example, the temperature of thetwo-phase dielectric material 290 can be decreased by the covers 700-1,700-2 and a heat sink 720. As illustrated in FIG. 7, the heat sink 720may be arranged on an outer surface of at least one of the covers 700-1,700-2 to discharge the heat extracted from the stator 200 and theelectronic device 400 by the two-phase dielectric material 290 to theoutside of the hermetic enclosure 270. The heat sink 720 may be providedwith heat exchanger fins or other cooling surfaces. The heat exchangerfins of the heat sink 720 may protrude to extend away from the cover700-1.

The two-phase dielectric material 290 may be a material configured to hetransitionable between a liquid phase and a gaseous phase in apredetermined operating temperature range. Those skilled in the art willrecognize that the two-phase dielectric material and the operatingtemperature range can be chosen appropriately for reducing thetemperature during the operation of the electric motor 100. The boilingpoint of the two-phase dielectric material may be, for example, but notlimited to, between 30° C. and 100° C. for preventing from deterioratingthe device performance and reliability of the electric motors 100. Thefluid may be capable of producing more uniform heat distribution (and/orreduced thermal resistivity) and therefore greater heat rejection thanmight otherwise be possible with heat transport via conduction alone.Beneficial in reducing core maximum temperatures. Furthermore,dielectric material selection can also be tuned to affect pressure ofthe enclosure via the materials Pressure and Temperature curve/vaporpressure curve.

The two-phase dielectric material 290 has dielectric characteristicsthat are able to directly contact with electronics withoutshort-circuit. The direct contact with the electronics allows heat to betransferred directly from the electronics into the two-phase dielectricmaterial 290. The two-phase dielectric material 290 are safe for contactwith electronics and efficiently and uniformly cool electronics usingtwo-phase immersion cooling. For example, the two-phase dielectricmaterial 290 may be Furan,2,3,3,4,4-pentafluorotetrahydro-5-methoxy-2,5-bis[1,2,2,2-tetrafluoro-1-(trifluoromethyl)ethyl]—(e.g.3M™ Novec™) or Propene, 1,1,2,3,3,3-hexa-fluoro, oxidized, polymerized(e.g. Galden® HT 100 of SOLVAY SOLEXIS, Inc.), but not limited thereto.Any two-phase dielectric material which is dielectric andhigh-performance heat transfer fluid with boiling points ranging from55° C. to 270° C. can be used.

By having the hermetic enclosure 270 containing the two-phase dielectricmaterial 290 together with the electronic device 400, some exemplaryembodiments of the present disclosure can efficiently cool theelectronic device 400 and the stator 200 without other means for forcedliquid cooling, such as a radiator, hoses, and a pump.

One of the covers 700-1, 700-2 may have the wire 756 for supplying powerto the electronic device 400 and electrically connected to the battery30 of the vehicle 10, and a connector 754 for ground and/orcommunication with other electronics installed at the vehicle. One endof the electrical wire of the connector 754 may be electricallyconnected to the circuit board 420, and the other end of the electricalwire of the connector 754 may be a pin which can be connected with anelectrical terminal of an electrical wire or cable.

The in-wheel motor 100 may be configured as a three-phase motor. Forexample, the three-phase motor may have three coils sets, and each coilset consists of a plurality of coil subsets that are connected inseries, where for a coil set the magnetic field generated by therespective coil sub-sets has a common phase. Each coil sub-set of theconductors 250 is wound around each tooth of the stator 200. However,the in-wheel motor 100 can include an arbitrary number of phases.Further, the electric motor 100 may be implemented as a dual orquadruple three phase motor for redundancy and thermal management.

The in-wheel motor 100 may preferably have 48 stator slots and 40 rotorpoles to achieve higher torque density and lower togging torque andtorque ripple. However, pole and slot numbers can be varied from 4 to 80and 6 to 90, respectively, if appropriate.

Although the electric motor according to some embodiments of the presentdisclosure is of the type having a set of coils being part of the statorfor attachment to a vehicle, radially surrounded by a rotor carrying aset of permanent magnets for attachment to a wheel, some of the aspectsof the present disclosure can be applied to an arrangement having therotor centrally mounted within radially surrounding coils of the stator.Further, the present disclosure could be incorporated in any form of anelectric motor. The electric motor can also be configured as agenerator.

Although the example embodiments have been described in detail, itshould be understood that various changes, substitutions and alterationscan be made herein without departing from the spirit and scope of theapplication as defined by the appended claims.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, and composition of matter, means, methods and stepsdescribed in the specification. As one of ordinary skill in the art willreadily appreciate from the disclosure, processes, machines,manufacture, compositions of matter, means, methods or steps, presentlyexisting or later to be developed, that perform substantially the samefunction or achieve substantially the same result as the correspondingembodiments described herein may be utilized according to theembodiments and alternative embodiments. Accordingly, the appendedclaims are intended to include within their scope such processes,machines, manufacture, compositions of matter, means, methods, or steps.

What is claimed is:
 1. A vehicle wheel assembly comprising: a wheel formounting a tire thereon and having an inner space; an in-wheel motormounted in the inner space of the wheel and configured to drivinglyrotate the wheel, the in-wheel motor comprising: a rotor connected tothe wheel, wherein a magnet is mounted to a center portion of the rotorrotatably coupled with a bearing assembly and arranged at a rotationaxis of the wheel, a stator configured to drive the rotor, wherein therotor is configured to be rotatable relative to the stator, a rotarysensor disposed in sensing relationship with the magnet mounted to thecenter portion of the rotor, the rotary sensor configured to beresponsive to rotation of the magnet for generating a signal, and anelectronic device comprising a circuit board and electronics mounted onthe circuit board; and a brake actuator configured to apply brake to thewheel or the rotor, wherein the electronic device configured to controlthe in-wheel motor and the brake actuator is positioned in an innercavity formed in the stator.
 2. The vehicle wheel assembly of claim 1,further comprising: two-phase dielectric material; and one or morecovers coupled with the stator to form a hermetic enclosure, wherein theelectronic device and the two-phase dielectric material are contained inthe hermetic enclosure formed by a wall of the stator and the one ormore covers coupled with stator, and the two-phase dielectric materialis in contact with the wall of the stator and the electronic device sothat the two-phase dielectric material changes temperature of the statorand the electronic device by transitioning between a liquid phase and agaseous phase.
 3. The vehicle wheel assembly of claim 2, furthercomprising a wire electrically connecting the circuit board containedwithin the hermetic enclosure and the rotary sensor disposed outside thehermetic enclosure so that an electronic control unit mounted on thecircuit board receives the signal generated by the rotary sensor.
 4. Thevehicle wheel assembly of claim 1, wherein the electronics mounted onthe circuit board comprise a single electronic control unit configuredto control both the in-wheel motor and the brake actuator.
 5. Thevehicle wheel assembly of claim 1, wherein the rotary sensor and themagnet of the rotor mounted to the center portion of the rotor arearranged to be collinear with the rotation axis of the wheel.
 6. Thevehicle wheel assembly of claim 1, wherein the magnet of the rotormounted to the center portion of the rotor and the rotary sensor aredisposed between the bearing assembly and a vehicle.
 7. The vehiclewheel assembly of claim 1, wherein: at least a part of the centerportion of the rotor, which is coupled with the bearing assembly and themagnet is mounted to, is positioned inside the inner cavity of thestator, and other magnets included in the rotor radially surround anouter surface of the stator.
 8. A vehicle wheel assembly comprising, awheel for mounting a tire thereon and having an inner space; and anin-wheel motor mounted in the inner space of the wheel and configured todrivingly rotate the wheel, the in-wheel motor comprising: a rotorconnected to the wheel, wherein a magnet is mounted to a center portionof the rotor rotatably coupled with a bearing assembly and arranged at arotation axis of the wheel; a stator configured to drive the rotor,wherein the rotor is configured to be rotatable relative to the stator;and a rotary sensor disposed in sensing relationship with the magnetmounted to the center portion of the rotor, the rotary sensor configuredto be responsive to rotation of the magnet for generating a signal. 9.The vehicle wheel assembly of claim 8, wherein the rotary sensor and themagnet of the rotor mounted to the center portion of the rotor arearranged to be collinear with the rotation axis of the wheel.
 10. Thevehicle wheel assembly of claim 8, wherein the magnet is mounted to adistal end of the center portion of the rotor.
 11. The vehicle wheelassembly of claim 8, wherein the rotary sensor and the magnet of therotor mounted to the center portion of the rotor are disposed betweenthe hearing assembly and a vehicle frame or body.
 12. The vehicle wheelassembly of claim 8, wherein: at least a part of the center portion ofthe rotor, which is coupled with the bearing assembly and the magnet ismounted to, is positioned inside an inner cavity of the stator, andother magnets included in the rotor radially surround an outer surfaceof the stator.
 13. The vehicle wheel assembly of claim 8, furthercomprising: two-phase dielectric material; an electronic devicecomprising a circuit board and electronics mounted on the circuit board;and one or more covers coupled with the stator to form a hermeticenclosure, wherein the electronic device and the two-phase dielectricmaterial are contained in the hermetic enclosure formed by a wail of thestator and the one or more covers coupled with stator, and the two-phasedielectric material is in contact with the wail of the stator and theelectronic device so that the two-phase dielectric material changestemperature of the stator and the electronic device by transitioningbetween a liquid phase and a gaseous phase.
 14. The vehicle wheelassembly of claim 13, further comprising a wire electrically connectingthe circuit board contained within the hermetic enclosure and the rotarysensor disposed outside the hermetic enclosure so that an electroniccontrol unit mounted on the circuit board receives the signal generatedby the rotary sensor.
 15. A vehicle wheel assembly comprising, a wheelfor mounting a tire thereon and having an inner space; and an in-wheelmotor mounted in the inner space of the wheel and configured todrivingly rotate the wheel, the in-wheel motor comprising: a rotorconnected to the wheel, a stator configured to drive the rotor, whereinthe rotor is configured to be rotatable relative to the stator, and anelectronic device comprising a circuit board and electronics mounted onthe circuit board: and a brake actuator configured to apply brake to thewheel or the rotor, wherein the electronic device configured to controlthe in-wheel motor and the brake actuator is positioned in an innercavity formed in the stator.
 16. The vehicle wheel assembly of claim 15,wherein the electronics of the electronic device positioned in the innercavity formed in the stator comprise a single electronic control unitconfigured to control both the in-wheel motor and the brake actuator.17. The vehicle wheel assembly of claim 15, wherein the electronics ofthe electronic device positioned in the inner cavity formed in thestator comprise: a first switch module configured to control currentsupplied to conductors of the stator, a second switch module configuredto control power supplied to the brake actuator, and a single electroniccontrol unit configured to control the first switch module for thestator and the second switch module the brake actuator.
 18. The vehiclewheel assembly of claim 1, further comprising: two-phase dielectricmaterial; and one or more covers coupled with the stator to form ahermetic enclosure, wherein the electronic device and the two-phasedielectric material are contained in the hermetic enclosure formed by awall of the stator and the one or more covers coupled with stator, andthe two-phase dielectric material is in contact with the wall of thestator and the electronic device so that the two-phase dielectricmaterial changes temperature of the stator and the electronic device bytransitioning between a liquid phase and a gaseous phase.
 19. Thevehicle wheel assembly of claim 18, further comprising a wireelectrically connecting the circuit board contained within the hermeticenclosure and the brake actuator disposed outside the hermetic enclosureso that a single electronic control unit mounted on the circuit boardcontrols the brake actuator.
 20. The vehicle wheel assembly of claim 1,wherein the in-wheel motor is configured to have 48 stator slots and 40rotor poles.